Previous machines are known for preparing and applying clips onto the neck of a plastic bag. For example, U.S. Pat. Nos., 3,163,969 and 3,163,972 disclose methods and apparatus for applying bag closures, or clips, onto the open neck portion of a plastic bag inside of which articles have previously been inserted. According to these methods and apparatus, a contiguous strip of clips is made of relatively brittle plastic material, and a clip is delivered and severed by bending and snapping the clip from the strip of clips. However, small fragments or pieces of material can sometimes break loose when snapping the clip, and the fragment can then contaminate a packaging operation. Attempts have been made to form bridges between adjacent clips in order to add predictability to the fracture process. However, these bridges can sometimes serve to form the fractured fragments. Secondly, a fractured surface is not always formed along a predictable path, which means that some clips can be imparted with a rough or even sharp edge that can be uncomfortable or dangerous in the hands of a user that is re-applying or removing a clip from a bag.
As the operating speeds of thermoforming machines and bagging machines have increased, this problem has been exacerbated as the increased speeds frequently lead to an increase in the misapplication and severing of clips from a strip of clips. In the process of designing newer and faster thermoforming lines and bagging machines for thermoformed articles, it has been realized that improvements are now needed in the design of bag closing machines in order to more accurately, quickly, and repeatedly apply clips onto plastic bags that contain articles. Furthermore, there exists a need to generate a more predictable and predetermined edge surface on a clip when severing the clip from a strip of clips. Even furthermore, environmental pollution concerns have lead to a need to provide a new mechanism for severing clips from a strip of clips which will enable construction and use of clips that are more environmentally friendly. Presently used frangible clips are constructed from plastic which is not environmentally friendly.
Accordingly, improvements are needed in the manner in which a clip is delivered onto an open neck portion of a plastic bag via a bag closing machine, wherein a clip is applied onto the open neck portion of the bag to close the bag and is then severed from a strip of clips.